In the manufacture of silicon carbide, the resistance furnace method, disclosed in Acheson U.S. Pat. No. Re. 11,473 of Feb. 26, 1895, the product pig is normally of roughly circular cross section surrounded by unreacted mix. There is a crust (white zone) high in silica on the outside surface of the pig, and inside of that is a partially reacted zone of "firesand" typically containing 40% silicon carbide. Inside of the firesand zone is a region of essentially 100% reacted material. At the center of the pig is a graphite core, the remains of the resistance element of the furnace.
The present invention provides a mechanical means of separating the unreacted material in the fire sand zone from the silicon carbide in the pig, after removal of the crust (white zone) and the graphite.